Since a photographic process using silver halide is excellent as compared to other photographic processes such as an electrophotographic process and a diazophotographic process in photographic characteristics such as light sensitivity and gradation control, the former process is most widely used. Recently, a technique capable of more simply and quickly obtaining images has been developed, in which the image-forming process for a silver halide photographic light-sensitive material is changed from conventional wet processing to dry processing using heating.
A heat-developable light-sensitive material is known in the field of the art and heat-developable light-sensitive materials and processes of development using them are described, e.g., in Shashin Kogaku no Kiso (Foundation of Photographic Engineering, pages 553 to 555 (published by Corona K. K., 1979), Eizoo Jooho (Image Information), page 40, published April 1978, Nebletts, Handbook of Photography and Reprography, 7th Ed., pages 32 and 33, published by Van Nostrand Reinhold Company, U.S. Pat. Nos. 3,152,904, 3,301,678, 3,392,020, and 3,457,075, British Patents 1,131,108, 1,167,777, and Research Disclosure, (RD-17029), pages 9 to 15, June, 1978.
Also, various processes of obtaining color images by heating are proposed, e.g., in Research Disclosure, (RD-16966), pages 54 to 58, May, 1978, ibid., (RD-14433), pages 30 to 32, April, 1976, U.S. Pat. Nos. 3,985,655, 4,463,079, 4,474,867, 4,478,927, 4,507,380, 4,500,626, and 4,483,914.
In these methods, imagewise distributions of dyes are formed by forming or releasing the dyes by heating and the imagewise distributions of dyes are obtained in a short period of time.
However, in conventionally used sensitizing dyes for the regions of from near infrared to infrared, the reduction of the color sensitivity from the wavelength at the maximum spectral sensitivity to the long wave side is not sharp. When a light-sensitive material has a layer having a spectral sensitivity in the region of a longer wavelength than the above described light-sensitive layer together with the light-sensitive layer, there is a problem that the color separation of the layer from the light-sensitive layer is insufficient.